The invention relates to the use of a mixture of lithium and nitrogen as anode material in rechargeable and non-rechargeable high energy density batteries.
The problems associated with the use of pure lithium metal anodes in electrochemical systems, and, in particular, in rechargeable cells have been well documented in the scientific and technical literature (see, for example, U.S. Pat. Nos. 4,550,064, 4,499,161, 4,118,550, 4,071,664, 4,086,403). The fundamental problem is the thermodynamic and kinetic instability of lithium towards cell materials and the electrolyte especially at the anode/electrolyte interface. In electrochemical cells, this results in corrosion/passivation of the lithium electrode. Thus, attempts to recycle lithium result in dendritic growth, formation of poorly adherent high surface area deposits of lithium metal on charging and slow chemical decomposition of the electrolyte. Ultimately, cell failure occurs due to cell shorting, depletion and/or isolation of the anode and anode passivation from electrolyte breakdown products. Short term solutions to the above problems have been to use excess lithium metal and/or conductive/protective films. Another approach has been to use composite electrodes like lithium-aluminum alloy. In such cases, an immobile host material promotes a uniform distribution of lithium having reduced chemical activity. Lithium aluminum alloys have been extensively investigated in nonaqueous electrolyte systems. However, the electrode experiences large volume changes during deposition/stripping associated with phase transformations. Such electrodes, on extensive recycling, exhibit severe mechanical instability. Other disadvantages associated with the use of alloys include large voltage and capacity losses relative to pure lithium anodes.